This invention relates to tool components comprising a composite abrasive compact.
Composite abrasive compacts consist of an abrasive compact layer bonded to a substrate which is generally a cemented carbide substrate. The abrasive compact layer comprises a mass of abrasive particles, typically diamond or cubic boron nitride, bonded into a hard conglomerate. Such layers are polycrystalline in nature and contain a high abrasive particle content. Diamond compacts are also known as polycrystalline diamond or PCD. Cubic boron nitride compacts are also known as polycrystalline cubic boron nitride or PCBN.
Composite abrasive compacts are manufactured under elevated temperature and pressure conditions, e.g. diamond or cubic boron nitride synthesis conditions.
Composite abrasive compacts are used in a variety of cutting, drilling, milling and other such operations. It is an edge or point formed on the abrasive compact layer of such composite compacts which performs the cutting, drilling, milling or other such operation.
Composite diamond abrasive compacts are used extensively in drilling. While they generally perform admirably in drilling, the diamond compact layer does tend to spall or break under some of the stressful conditions which can be encountered during drilling.
U.S. Pat. No. 4,861,350 describes a tool component in the form of a composite abrasive compact wherein the abrasive compact has two zones which are joined by an interlocking, common boundary. The one zone provides the cutting edge or point for the tool component, while the other zone is bonded to a cemented carbide substrate. In one embodiment, the cemented carbide substrate has a central portion extending into the abrasive compact defining a peripheral abrasive compact stepped region surrounding the central portion.